1. Field of the Invention
The invention relates to connector housings adapted for use in electrically connecting wire harnesses for automobiles. More particularly, the invention is directed to a connector housing with a lock (hereinafter referred to simply as a "housing") which prevents a lock arm disposed on an outer surface of the connector housing from being broken due to excessive flexion at the time of a locking or unlocking operation.
2. Related Art
A conventional flexible lock arm arranged on an outer wall of a housing for engaging and locking connectors with each other is supported at both ends thereof. Such a flexible lock arm is disclosed in, e.g., Japanese Unexamined Utility Model Publication No. 62-18979 and the like. As shown in FIG. 5, the front portion of a male housing 31 having terminal accommodating chambers 42 formed therein is designed to be inserted into a hood member 33 arranged at the front portion of a female housing 32 having terminal accommodating chambers 43 formed therein. Each terminal accommodating chamber 42 accommodates a connecting terminal, and each terminal accommodating chamber 43 accommodates a connecting terminal of such a different type as to correspond to the aforementioned connecting terminal. On one wall surface of the hood member 33 is a retaining chamber 35 having a retaining portion 34.
Further, on one outer wall surface 37 of the male housing 31 is a lock arm 39 whose front and rear ends are supported by support portions 37, 38. The lock arm 39 has a retaining projection 40 that is to be retained by the retaining portion 34 and an unlocking portion 41 for releasing the engagement of both connectors.
Since a thickness 39a of the lock arm 39 is such that both the front and rear ends thereof are greater and the vicinity of the middle portion thereof is smaller, the vicinity of the middle portion thereof is particularly flexible even if the lock arm 39 is made of a hard synthetic resin.
In the aforementioned construction, when the male housing 31 is inserted into the hood member 33 of the female housing 32, first, the inclined surface at the front end of the retaining projection 40 is first abutted against the front end of the retaining portion 34 to be pressed downward. Then, the retaining projection 40 is retained by the retaining portion 34, thereby causing the male housing 31 to be engaged with and locked by the female housing 32.
Further, to release the engagement of both connectors, an unlocking portion 41 is pressed, so that the lock arm 39 is so flexed to as to release the retaining projection 40 from the retaining portion 34. When the male housing 31 is pulled out under this condition, the male housing 31 is separated from the female housing 32.
As shown in FIG. 6, the lock arm 39 is pressed and flexed during the engaging and locking operation or during the unlocking operation. Since the thickness 39a is made smaller in the vicinity of the rear end of the retaining projection 40, the movement of the retaining projection 40 is almost equal to a parallel movement. Therefore, a displacement necessary for unlocking the lock arm 39 is determined by the height h.sub.1 of the retaining projection 40, requiring a smaller flexing space h.sub.2 compared with a displacement necessary for unlocking a cantilevered lock arm. As a result, not only the housing can be downsized, but also an engagement gap .delta., which is a cause of backlash after the engagement and locking, can be made small, which in turn prevents wear and noise of the lock mechanism.
However, the aforementioned conventional lock arm 39 requires a large inserting force so that the retaining projection 40 can pass under the retaining portion 34 of the female housing 32 at the time of engaging and locking the lock arm 39. As a result, a large inserting load is applied to the support portion 37 at the front end of the lock arm 39, imposing a problem that the lock arm 39 is plastically deformed or broken by the excessive inserting force as shown in FIG. 7(a).
Further, at the time of unlocking the lock arm 39, a large unlocking load is applied to the support portion 38 at the rear end as the lock arm 39 is pressed by the unlocking portion 41, imposing a problem that the lock arm 39 is plastically deformed or broken by the excessive releasing force as shown in FIG. 7(b).
Moreover, while it is desirable that the inserting load is appropriately large and that the releasing load is small, there is little difference between the inserting load and the releasing load in the lock arm 39 support structure shown in FIG. 6, and since greater consideration is given to the locking operation at the time of insertion, imposing a problem that unlocking operability is not satisfactory.
Still further, since the thickness 39a along the length of the lock arm 39 is tapered, imposing a problem that reliability in the strength of the thin portion of the retaining projection is impaired.
An object of the invention is to provide a connector housing with a lock capable of ensuring an inserting load necessary for locking, improving unlocking performance, and ensuring reliability in the strength of the lock arm.